Thalassaemia in Pregnancy

Thalassaemia in pregnancy is an inherited reduction in globin chain synthesis (alpha or beta) causing microcytic anaemia, in a pregnant woman. Carriers (trait) are common and usually have mild anaemia, while thalassaemia intermedia and major cause severe anaemia, iron overload and organ damage. It matters because carrier couples risk a baby with major disease, and women with major disease need transfusion and chelation adjustment.

• Trait: haemoglobin 9 to 11 g/dL with very low MCV and normal ferritin.
• Beta thalassaemia major is rare in Kenya but occurs.
• Testing the partner decides fetal risk.

Women with trait are well apart from mild pallor. Those with intermedia or major have pallor, jaundice, bone changes, splenomegaly, delayed puberty and, if overloaded with iron, heart, liver and endocrine disease.

• Splenomegaly and frontal bossing.
• Bronze skin from iron overload.
• Differential diagnosis: iron deficiency anaemia, sickle cell disease, HbE disease, anaemia of chronic disease, lead poisoning, sideroblastic anaemia.
• Complications: severe anaemia, heart failure, arrhythmia, diabetes, hypothyroidism, hypoparathyroidism, osteoporosis, preterm birth, fetal growth restriction, alloimmunisation, thrombosis, affected baby.

The approach is blood count, haemoglobin electrophoresis and partner testing.

• Full blood count: MCV below 80 fL with raised red cell count; HbA2 above 3.5 percent in beta thalassaemia trait; HPLC or electrophoresis.
• Ferritin to exclude iron deficiency; DNA analysis for alpha thalassaemia where available.
• Partner haemoglobin testing; chorionic villus sampling at 11 to 13 weeks or amniocentesis at 15 to 20 weeks if both partners carry beta thalassaemia.
• Intermedia or major: echocardiography, ECG, ferritin, liver enzymes, fasting glucose or 75 g oral glucose tolerance test, TSH, calcium, red cell antibodies, spleen and fetal growth scans.

The principle is folic acid, transfusion when needed, iron only if deficient, and prenatal diagnosis for carrier couples.

• Supportive: nutrition; avoid iron unless deficient; vaccinate (hepatitis B, pneumococcus, influenza); regular dental and eye checks.
• Pharmacological: folic acid 5 mg oral daily; trait: ferrous sulphate 200 mg oral 8-hourly only if ferritin is below 30 micrograms/L; major or intermedia: transfuse to keep pre-transfusion haemoglobin at 10 g/dL; stop deferasirox and deferiprone before conception, and give deferoxamine 20 to 40 mg/kg subcutaneous over 8 to 12 hours, 5 to 7 nights weekly, only after the first trimester if cardiac iron is high; aspirin 75 mg oral at night from 12 weeks; enoxaparin 40 mg subcutaneous daily during admission and for 6 weeks after delivery in women with splenectomy or major disease; insulin for diabetes; levothyroxine 1.6 micrograms/kg oral daily for hypothyroidism.
• Procedures: simple red cell transfusion every 2 to 4 weeks for major or intermedia disease; chorionic villus sampling for couples at risk; caesarean section for cephalopelvic disproportion; splenectomy is avoided in pregnancy.
• Special groups: alpha thalassaemia with hydrops fetalis risk (both parents with alpha zero trait) needs scan from 12 to 13 weeks for cardiomegaly and hydrops, and counselling on the outlook and options is needed.
• Red flags: breathlessness, palpitations, ankle swelling, fever, haemoglobin below 7 g/dL, fetal hydrops.
• Follow-up: haemoglobin every 4 weeks; cardiac and endocrine review each trimester; growth scans every 4 weeks from 28 weeks; neonatal screening; contraception advice.